This is an idea: I would like to continue to support and use the Arduino as a prototyping platform, but ultimately strip the things I do not need for my final projects like serial/usb communications, extra IO pins, blah blah blah to ultimately save space and cost (all my projects will ultimately be for my edification, proof of concepts for myself and hopefully to aid the online community).

My question is what is the bare minimum to have? Is it just the microprocessor, and I just have to use the pins I need for each project?

You need a regulated power supply, which could mean putting a voltage regulator somewhere in your circuit (unless you have another source for it).

In the current Arduino core a few things don't work if you're not using an external oscillator at 16 MHz. I'm planning to fix this for Arduino 0010 and the Arduino LilyPad (which will be using the internal clock of the ATmega168).

A reset button is often convenient, though you can just tie the reset pin high and remove power to the board to reset it.

An ICSP header (the six male pins on the Arduino board) can be useful, but you don't need them if you don't mind moving the ATmega to another circuit to reprogram it.

Sorry to necropost here, but I have basically the same question. Arduino is fantastic, but it would get pretty expensive pretty quick to buy a whole board for something I intend to put together permanently.

I saw this approach taken on the Make blog a while back, but I see it's an ATmega8, not a 168. Besides regulated power, would the 168 require anything more than what's on this little setup? Could the 168 be programmed, popped off the Arduino board and run on just this?

The boards are intended as a prototyping platform. While you COULD buy a full board every time you had a little hobby idea, that's not the expectation.

Same basic requirements between the two chips. I would have to check, but he's showing two Vcc pins and a GND that aren't actually connected but probably should be. Jumpers OVER the chip would work there.

You could even not install the pin 13 LED and it's current limiting resistor, that would leave just 4 components and that counts the included MEGA168 (with Arduino bootloader installed), all for under $10. I bought it for permanent attachment to my large solder-less breadboard which already has regulated voltages and I had a DIP packaged USB serial module.

If you're that basic though, why build it on its own board? For 4 components, just put the bare components on the perfboard or breadboard (and then you're under $5). Also, the stamp seems to lack proper crystal which is important if you want the Arduino timings to work precisely.

Fundamental Logic is a great store, I've had very good experiences when purchasing from them, and for breadboard work, I strongly recommend their iDuino board over this stamp -- it's a few dollars more and gives you a full blown arduino that sits on a breadboard. And pick up a few extra MCU's for finished projected.

If you're that basic though, why build it on its own board? For 4 components, just put the bare components on the perfboard or breadboard (and then you're under $5). Also, the stamp seems to lack proper crystal which is important if you want the Arduino timings to work precisely.

I just wanted the smallest footprint available for a self contained module. It works but of course the wonderful thing about this open source project is the wide choice of vendors supporting the hardware, so one is free to choice from many different designs.

On the resonator Vs crystal, I too would prefer a crystal but so far the resonator has been problem free communicating back to the PC at 57600 baud with no timing errors.